Hand brewing skills | How to use the relationship between coffee concentration and extraction rate to brew coffee?

How to brew a delicious cup of coffee?

There is a standard extraction rate and concentration argument for "good coffee": the Gold Cup Theory, which holds that "good coffee" must meet two conditions at the same time:

1. The extraction rate is between 18% and 22%.

2. The coffee concentration is in the range of 1.2% to 1.45%.

So what is coffee extraction rate and concentration?

Coffee extraction rate

The extraction rate refers to how much of the coffee powder you use to brew is dissolved into the coffee.

Coffee strength

The amount of hot water in which the extracted extract will dissolve indicates the proportion of "extracted coffee substances" to the total coffee liquid in a cup of coffee.

The Gold Cup standard is the most acceptable coffee concentration and coffee extraction rate in each country based on the taste of regional consumers. In terms of coffee powder to water ratio, according to the Gold Cup standard: 50-60 grams of coffee are needed for every liter of water (1000g), and the "Gold Cup" is a simplified digital template of multiple extraction rates: 1:14, 1:15-1:16-1:17-1:18-1:19-1:20, depending on the subject's preference for coffee concentration.

From this picture, we can see that the middle is the golden zone of coffee extraction, with a concentration of 1.15%-1.35% and an extraction rate of 18%-22%. Coffee in this range tastes sweet and smooth and is loved by everyone.

For example, if you use 100g of coffee powder to brew, after brewing the coffee, remove the moisture from the coffee grounds (regardless of whether it is oven-dried or sun-dried), if there are 80g left, it means that 20g of the substance has been dissolved into the coffee, then the extraction rate of this cup of coffee is 20%.

Extraction Yield and Coffee Taste

We often talk about "over-extraction" and "under-extraction/under-extraction", which refers to excessive or under-extraction of coffee. To get the best taste from coffee, you need to accurately extract the beneficial "substances" in coffee. If your coffee tastes bad, for example:

Under-extracted coffee (extraction rate less than 18%) usually has a sour, thin, light flavor, and is monotonous and featureless. Try extending the extraction time or using a finer grind.

Over-extracted coffee (extraction rate above 22%) will taste more bitter, gray, and astringent. At this time, you can try a coarser grind or shorten the extraction time.

Extraction rate = amount of coffee dissolved in water / total amount of coffee powder

EXT%=TDS(g) / Dose(g) × 100%

Adjusting coffee extraction rate

1. Adjust the grinding degree (that is, the contact area between coffee and water);

2. Adjust the brewing time (that is, the contact time between coffee and water);

3. Adjust the water temperature

The relationship between concentration and taste

Appropriate coffee strength (black coffee, referring to brewed coffee): 1.15-1.35 (SCAA standard); 1.2-1.45 (SCAE) standard.

Concentration is too high (when the concentration of black coffee exceeds 1.5%): the coffee tastes too strong, especially the sourness and bitterness, and the sweetness is insufficient; the flavor of good coffee is not obvious, which can easily be misunderstood as "over-extraction".

The concentration is too low (when the concentration of black coffee is lower than 1.15%): the coffee tastes too light, the sourness, sweetness and bitterness are not obvious, and the coffee flavor characteristics are not obvious, which can easily be misunderstood as "too little extraction/insufficient extraction".

Coffee concentration = mass of coffee solute / mass of coffee solution

TDS%=TDS(g) / Yield(g) × 100%

Adjust density

Adjust the powder-water ratio (when other conditions are constant, more powder and less water means higher concentration; less powder and more water means lower concentration.)

If the weight of the coffee powder you use is for one person (about 15 grams), you can refer to the following suggestions .

1. Grinding degree: The grinding degree that is about the same size as the sugar particles is suitable for a wide range of applications. You can use your fingers to rub the sugar particles and coffee powder particles to compare.

2. Brewing time: Generally, the brewing time is between 1 minute 40 seconds and 2 minutes. The longer the brewing time, the more substances will be extracted from the coffee, and the stronger the coffee taste will be when the amount of water injected remains the same, but it will also increase the risk of the taste becoming noticeably bitter.

3. Brewing temperature: You will need to adjust your brewing temperature according to the degree of roasting of your coffee beans. You can refer to the following data for how to adjust it:

Light roast: 90-92 degrees Celsius

Medium light roast: 87-90 degrees Celsius

Medium roast: 85-87 degrees Celsius

Medium-dark roast: 83-85 degrees Celsius

Dark roast: 80-83 degrees Celsius

Generally speaking, the roasting degree will be marked on the outer packaging of coffee beans. If you feel that the coffee brewed at a certain temperature is obviously bitter, you can try to lower the water temperature. If it is too light and the taste is thin, you can try to slightly increase the water temperature. Adjusting 2 degrees at a time is a good choice.

4. About the amount of water to be injected (water-to-powder ratio): The ratio between the amount of water you are going to inject and the coffee powder you are using is the water ratio. Adjusting this ratio can easily change the concentration of your coffee liquid. If you are using a general or entry-level grinder and are just starting to learn hand brewing, it is safer to use a ratio of 12:1 to 14:1 between water and powder (that is, 15g of powder is injected with 180-210g of water). This will ensure that the coffee has sufficient concentration without being easily bitter.

Hand brewed coffee water powder ratio parameters

[Heavy taste] 1:10-1:11 (coffee beans in grams to black coffee in milliliters), which is the Golden Cup standard of 1:12.5-1:13.5 (bean weight to raw water in milliliters)

[Moderate taste] 1:12~1:13 (i.e. 1:14.5~1:15.5 according to the Gold Cup standard)

[Small Fresh] 1:14～1:16 (i.e. 1:16.5～1:18.5 of the Gold Cup standard)

Rules for hand brewing: Generally speaking, when hand brewing, with a fixed amount of coffee and water-to-powder ratio, the higher the water temperature, the longer the brewing time, and the finer the grind, the more substances in the coffee will be brought out, making the brewed coffee stronger and showing a more complete coffee flavor, but it is more likely to be bitter. High concentration does not necessarily mean over-extraction; bitter coffee does not necessarily mean over-extraction, so you need to try a few times to find a balance.

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